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The Bowstring Truss

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The Bow String Truss

The Bowstring Truss:
There’s a tremendous lack of understanding in the American Fire Service as to what accurately defines and comprises a Heavy Timber Bowstring Truss and the Operational and Safety Precautions that must be recognized, implemented and trained on, in order to achieve and maintain operational excellence, company integrity and firefighter safety on the fireground.

All bowstring trusses are not created equal and do not share the same characteristics when found in a building and occupancy.

They may have the same shape, but shape alone does not define the bowstring truss.
Based on the type, design, construction, materials, age, span, spacing, configuration, occupancy and application there are vast differences AND similarities.

There are significant differences in terminology when referring to them and tactics that should be employed on the fireground- and yes there are prominent differences between east coast and west coast types and tactics.

The Bowstring Truss- They are not All the Same

Do you know what they are?

I’m working on an article series for a major fire service publication with on-line accompaniments that will provide uniformity and clarity on the subject and the much needed continuity so were’ talking the same language.For the mean time let me offer the following terms that some of you may be familiar with – in your world. Here are some Bowstring Type Truss terms:

  • The Heavy Timber Bowstring Truss,
  • Arch-Rib Bowstring Truss,
  • Laminate Cord Bowstring Truss,
  • Lattice Bowstring Truss,
  • Easybow Truss,
  • Mack Truss,
  • Summerbell Bowstring Truss,
  • Mono-chord Bowstring Truss
  • Duo-Chord Bowstring Truss,
  • Segmental Multi-Cord Bowstring Truss,
  • Tension Rod Bowstring Truss,
  • Bowstring Arch Truss,
  • Bowstring K-Truss,
  • Split-Ring Bowstring Truss…..to name a few.

We’ll be posting lots more on this on CommandSafety.com as well as expanded coverage on Buildingsonfire.com …. Stay Tuned

Don’t forget to LIKE Buildingsonfire on FaceBook and follow CommandSafety on Twitter

 

Taking it the Streets: Reading the Building

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Taking it the Streets: Reading the Building
Here’s a simple view from the Alpha street side. I’ll give you the options as to what you’re arrive on or as…Reading the Building requires numerous layers of knowledge and skill based attributes to develop the perspective to “read your buildings” differently.

Reading the Building: Occupancy Type and Occupancy Risk?

Arriving companies and personnel at a structure fire need to be able to rapidly and accurately identify key elements of a building, process that data based upon a widening field of variables present on today’s evolving fireground and implement timely actions that address prioritized actions requiring intervention.  

Deterministic fireground models for size-up and suppression have to give way to a more expandable stochastic model of assessment. Key to this is having a broad and well developed foundation of building knowledge.

Let’s identify the building type, age, key features based on its profile, inherent characteristics, projected performance, roof system, perimeter walls, hazards, risks..etc. What is the Occupancy Type and Occupancy Risk?

There is a wealth of information you can talk about-IF you know what to look for. Start the dialog. I’ll post interior views in 48 hours.

  • Check out the dialog and interaction on Buildingsonfire on Facebook. 
  • I’ve cross posted to allow for some robust discussions. Don’t forget to Like us on Facebook. 

Can you Read this building correctly? Or will your view have an adverse affect on operations if you misjudged or just didn’t know or care…just because ” you wanted to just stretch in and do the job-right?”

New for 2013: Reading the Building: Predictive Profiling for the Modern Fireground. An  engaging and interactive Training Seminar addressing the Challenges of Today’s Evolving Fireground. 

Engineered Structural Support (ESS) system: Been in the Field lately?

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Been in the field lately looking at your buildings under construction? Here’s a new look at a common Engineered Structural Support (ESS) system.

Here’s  today’s Taking it to the Streets session; Take a look at this Engineered Structural Support (ESS) system. There are two critical component systems depicted here in this photo- can you tell what they are? Take a close look at the ESS T…russ components. They are nothing new, but they do cause a stir when they make their way back into main stream fire service discussions as firefighters and officers “rediscover” these type of systems, their use, presence and operational risk and profiling.

So let’s start the dialog:

  • Can you name the type of ESS Truss, the inherent characteristics, design and function | typical applications | risks and operational concerns.
  • What impact will fire impingement have on the ESS assembly in either foor or roof systems?
  • How can you identify these assemblies and building characteristics unpon arrival?
  • What fireground strategies and tactics would you employ upon arrival at an occupancy with this type of ESS?
  • Don’t forget to look at the second system component that I mentioned earlier;
  • Can you identify it? Its relationship to the other system and other inherent performance issues?

 

 

Lots to talk about, look at and share. Any street stories to share-please post. I’ve got a few more in this series to post after we get some dialog and insights….
We’ve cross posted this on our Buildingsonfire Facebook page (HERE), if you haven’t checked it out, please follow the link, there’s been some great discussions and insights being shared from around the country…
Don’t forget to spread the word about Buildingsonfire.com \ CommandSafety.com and Buildingsonfire on FB…send the links along and like….Dont forget about CommandSafety on Twitter and Buildingsonfire on twitter also.

Building Construction for Today’s Fire Service

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Here’s the starting line-up of the New 2013 Buildingsonfire Training Programs and Seminars

Program Details coming early January

  • Building Construction for Today’s Fire Service
  • Reading the Building: Tactical Risk for the First-Due
    • Two New Programs Addressing The Needs for Today’s Evolving Fireground and Firefighter

      Building Construction for Today’s Fire Service
      Reading the Building: Tactical Risk for the First-Due

  • Building Construction for the Adaptive Fireground
  • Collapse Considerations for Buildings on Fire
  • Fireground Leadership for the Company and Command Officer
  • Adaptive Fireground Management for the Company and Command Officer
  • Engineered Systems: Buildings, Construction and Tactics

If you’re interested in hosting a program in 2013 or 2014, contact us at Buildingsonfire@gmail.com or CommandSafety@gmail.com

Building Knowledge = Firefighter Safety

Defining Buildings and their Inherent Characteristics

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Defining Buildings and Inherent Charactoristics

Today’s evolving fireground demands greater insights and an increased understanding of buildings, occupancy risk profiling (ORP) and building anatomy. Recently there has been a movement that has categorized buildings into two groups: engineered and legacy construction.

I strongly believe this is far too limiting and restrictive which is resulting in missed opportunities to develop further insights into other building systems and occupancy risk profiling. In order to refine categories that provide corresponding values related to inherent construction features, systems, collapse and comprise, performance characteristics, fire integrity, resistance etc., the following building anatomy categories are suggested and promoted:

Building Anatomy

Construction Systems

  • Heritage
    • Pre-1900
  • Legacy
    • 1900-1949
  • Conventional
    • 1950-1979
  • Engineered
    • 1980-2001
  • Integrated Hybrid Systems
    • 2002- current …
  • Composite Engineered Systems
    • 2010 – current …

Give some thought to the time spans and the types of buildings at would compromise each group. I’ll post an upcoming article with expanded narrative on each…..

Bridging The Gap: Fire Safety and Green Buildings Guide

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Bridging The Gap: Fire Safety and Green Buildings Guide

A Fire and Safety Building Guide to Green Construction

The National Association of State Fire Marshals (NASFM) has released its fire and building safety guide to green construction called “Bridging the Gap: Fire Safety and Green Buildings.” This guide identifies some of the key areas where rapidly growing green building construction issues coincide with building and fire safety needs.

“This guide will give both the fire service and the green construction community a reference point for developing buildings and sites that are not only environmentally sound, but also continue to meet fire safety needs,” said NASFM President Alan Shuman. “This will provide a much-needed reference on issues that impact the life safety of building occupants, emergency responders and the larger community.”

Included are topical areas such as Site Selection and Use, Building Envelope and Design Attributes, and Building Systems and Alternative Power Sources. A key feature of the guide is a series of checklists focusing on plan reviews for commercial and residential occupancies. This document is meant as an introductory guide for fire chiefs and firefighters, building and fire code enforcement officials, architects and anyone involved in building design, plan reviews and construction.

Click here to download a copy of the guide, which was developed for NASFM by Jim Tidwell of Tidwell Code Consulting, with Jack Murphy, as part of a larger program under a Department of Homeland Security Fire Prevention and Safety Grant.

Direct Link:  http://www.firemarshals.org/programs/green-buildings-fire-safety-project/guide/

http://www.firemarshals.org/

 

Building Construction Training for Fire Service Commanders, Company Officers and Firefighters

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We’ve got an advance look at some of the new training and lecture offerings coming out this fall and for 2012 that will be offered commencing in October for the Buildingsonfire Series produced and offered by the Command Institute and Buildingsonfire.com.

Buildingsonfire -2012  Building Construction and Systems Training for Fire Service Commanders, Company Officers and Fire Fighters

An intense and concentrated  series of exceptional training programs examining trends and methods in building construction for the fire service with an emphasize on construction and  occupancy risk assessment, structural and construction systems, and their direct relationship on structural combat firefighting operations, firefighter survivability and the command decision-making process. Understand building systems and occupancy performance under fire conditions is mission critical with new and emerging technical information and data that is redefining tactical and operational models and firefighting protocols with new rules of engagement.

Firefighters and Officers will gain a new understanding of inherent construction features and hazards that directly influence effective risk management and decisive strategic and tactical considerations with a focus on key construction features, inherent occupancy profiles that will influence strategic, tactical and task level operations and crucial assembly systems affected by fire dynamics, extreme fire behavior and combat fire suppression operations. These programs & seminars examine crucial considerations for Reading the Building, Occupancy Risk Profiling, Adaptive Fireground Management, Tactical Patience, Predicative Occupancy Performance and Construction Resiliency correlating building construction performance toward combat structural fire suppression operations. Case studies will reinforce concepts presented and evoked open discussion and dialog on building construction and operational safety.

Programs utilize extensive multimedia, interactive activities, case studies and simulations to reinforce course content & subject areas providing exceptional learning opportunities.

New Seminars and Lecture Program Offerings; (Selected Topics)

  • Building Construction for the Company  and Command Officer
  • The Rules of Combat Fire Engagement & Tactical Operations  
  • Reading the Building: Predictive Occupancy Profiling
  • The New Fireground: Engineered Systems, Construction &  Tactics for the Company  and Command Officer
  • Adaptive Fire Ground Management for Command and Company Officers
  • Building Construction and Tactical Operations
  • The Anatomy of Buildingsonfire 2012
  • Five Star Command & Fire Fighter Safety
  • The Doctrine of Combat Fire Operations 2012
  • Extreme Fire Behavior & Fireground Operations
  • Predictive Building and Occupancy Performance
  • Tactical Entertainment and Firefighter Safety
  • Dynamic Risk Assessment & Firefighting Operations
  • Roof Construction for Truck Company Operations
  • Occupancy Risk Profiling and Firefighting Strategy & Tactics
  • New Residential Construction and Operational Considerations
  • Tactical Renaissance:  Combat Fire Engagement and the New Fire Ground
  • The Anatomy of Buildingsonfire; LODD Case Studies and Near Miss Lessons Learned
  • Building Construction and Operational Safety in Buildings of Ordinary Construction
  • Building Construction and Tactical Safety in Commercial Buildings
  • Keynotes ,Lectures, Special Presentations & Programs Available
  • Other Building Construction , Command, Tactic, Fire Fighter Safety and Operations programs available  

Download the Program Announcement for Building Construction for the Fire Service Training Programs HERE

Building Construction for the Fire Service Training Programs for 2012 by Buildingsonfire.com

Keynote and General Session Programs that will be available for 2012 include;

Keynote Topics:

  • The New Adaptive Fire Ground in 2012
  • Tactical Patience
  • Buildingsonfire 2012
  • What’s on YOUR Radar Screen?
  • Achieving Operational Excellence and Safety
  • Command Compression and Tactical Entertainment
  • The Evolving Fireground: Are You Ready for the Changes?
  • Command Resiliency for Operational Excellence   
  • Tactical Renaissance and the New Rules of Combat Fire Engagement

Upcoming:

Check out the program presentations we’ll be making at the Gateway Midwest Fire & Leadership Training Conference ( Missouri) and at the Liberty Regional Fire & Leadership Training Conference (PA) this fall.

Take the time to check out the new Training Program Offerings from Go>Forward Training’s Gateway Midwest Fire & Leadership Training Conference, HERE and the Liberty Regional Fire & Leadership Training Conference  HERE

  • About Go>Forward Training, HERE

The Hyatt Regency Skywalk Collapse 1981; The Begining of Urban Heavy Rescue

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The Hyatt Regency Walkway Collapse July 1981

On July 17, 1981 a suspended walkway collapsed in The Hyatt Regency Hotel  in Kansas City, Missouri, killing 114 people and injuring 216 others during a tea dance. At the time, it was the deadliest structural collapse in U.S. history. This event and a subsequent series of other major incidents in the early and mid 1980′s began the formulative efforts towards defining the emerging field of Urban Heavy Rescue (UHR) that would transition into Urban Search  and Rescue (USAR) in the late 1980′s and early 1990′s. 

Another significant incident occurring in 1981 included the Harbor Cay Condominium Collapse (Cocoa Beach, Florida, 1981). This building was under construction at the time of collapse. Heavy floor and wall construction consisted of precast reinforced concrete slabs and cast-in-place concrete components. All five floors and the roof of the condominium collapsed in a pancake configuration, trapping a large number of construction workers. Eleven were killed and 23 injured. The incident involved more than 60 hours of continuous rescue operations and resources from 5 county fire districts; 16 municipal fire departments; and a response of Civil Defense, military, and private sector technical specialists.

Today marks the thirty year anniverary of the Kansas City event and the lessons learned that continue to be applied towards collapse rescue, urban search and rescue and techncial rescue operations, protocals, techniques, methodologies and preparedness.

On July 17, 1981, approximately 1,600 people gathered in the atrium to participate in and watch a dance competition. Dozens stood on the walkways. At 7:05 PM, the second-level walkway held approximately 40 people with more on the third and an additional 16 to 20 on the fourth level who watched the activities of crowd in the lobby below. The fourth floor bridge was suspended directly over the second floor bridge, with the third floor walkway offset several feet from the others.

Construction difficulties resulted in a subtle but flawed design change that doubled the load on the connection between the fourth floor walkway support beams and the tie rods carrying the weight of both walkways. This new design was barely adequate to support the dead load weight of the structure itself, much less the added weight of the spectators.

The connection failed and the fourth floor walkway collapsed onto the second floor and both walkways then fell to the lobby floor below, resulting in 111 immediate deaths and 216 injuries. Three additional victims died after being evacuated to hospitals making the total number of deaths 114 people.

Direct Link to the 1982 NIST Report, HERE

The hotel had only been in operation for approximately one year at the time of the walkways collapse, and the ensuing investigation of the accident revealed some unsettling facts:

  • During January and February, 1979, the design of the hanger rod connections was changed in a series of events and disputed communications between the fabricator (Havens Steel Company) and the engineering design team (G.C.E. International, Inc., a professional engineering firm). The fabricator changed the design from a one-rod to a two-rod system to simplify the assembly task, doubling the load on the connector, which ultimately resulted in the walkways collapse.
  • The fabricator, in sworn testimony before the administrative judicial hearings after the accident, claimed that his company (Havens) telephoned the engineering firm (G.C.E.) for change approval. G.C.E. denied ever receiving such a call from Havens.
  • On October 14, 1979 (more than one year before the walkways collapsed), while the hotel was still under construction, more than 2700 square feet of the atrium roof collapsed because one of the roof connections at the north end of the atrium failed.
  • In testimony, G.C.E. stated that on three separate occasions they requested on-site project representation during the construction phase; however, these requests were not acted on by the owner (Crown Center Redevelopment Corporation), due to additional costs of providing on-site inspection.
  • Even as originally designed, the walkways were barely capable of holding up the expected load, and would have failed to meet the requirements of the Kansas City Building Code.

 The Kansas City Star has a dedicated memorial website established with images, video and information; HERE 

A look back at the Hyatt Regency Skywalk Disaster, HERE

Kansas City (MO) Fire Department, HERE

Photos from Hyatt Regency Skywalk collapse aftermath, HERE

The high number of dead and injured, the location of the collapse, the size of the collapsed material, and the ineffectiveness of the typical emergency service tools created severe rescue limitations.

The incident required a large number of medical personnel working alongside the rescuers.

Twenty-nine live victims were removed from under the debris during the rescue operations. Heavy rigging and construction specialists and heavy equipment were needed to remove the debris during the rescue operations. large scale rescue operation soon unfolded. Heroes of the evening ranged from a husband who pulled his wife’s trapped foot from the wreckage, to a surgeon who performed an emergency amputation to save a trapped and bleeding victim, to construction crew workers who toiled throughout the night clearing the debris.

A local crane company arrived at the scene to remove sections of collapsed walkway. Dispatchers called in emergency vehicles from throughout the city. Outlying cities such as Belton and Lee’s Summit offered help within minutes of the dispatch calls. Victims were rushed to four nearby hospitals. Donors poured into the Greater Kansas City Community Blood Center. Local talk-show host Walt Bodine broadcast throughout the night. As late as midnight, excavators were trying to reach over a dozen people still trapped under the debris. At 5 a.m., workers uncovered the final 31 bodies from the last slab of concrete to be removed.

The rescue operation lasted well into the next morning and was carried out by a veritable army of emergency personnel, including 34 fire trucks, and paramedics and doctors from five area hospitals. Dr. Joseph Waeckerle directed the rescue effort setting up a makeshift morgue in the ruined lobby and turning the hotel’s taxi ring into a triage center, helping to organize the wounded by highest need for medical care. Those who could walk were instructed to leave the hotel to simplify the rescue effort, the fatally injured were told they were going to die and given morphine.

Workmen from a local construction company were also hired by the city fire department, bringing with them cranes, bulldozers, jackhammers and concrete-cutting power saws.

The biggest challenge to the rescue operation came when falling debris severed the hotel’s water pipes, flooding the lobby and putting trapped survivors at great risk of drowning. As the pipes were connected to water tanks, as opposed to a public source, the flow could not be shut off.

Eventually, Kansas City’s fire chief realized that the hotel’s front doors were trapping the water in the lobby. On his orders, a bulldozer was sent in to rip out the doors, which allowed the water to pour out of the lobby and thus eliminated the danger to survivors.

 

Diagram of the Atrium before the Collapse from the Kansascitystar.com

 

After the Collapse. Diagram from the Kansascitystar.com

Investigators photograph the hanger rods while standing in an aluminum platform designed to change burned out lights in the 5th floor ceiling. Note that the channel beam sections have completely slipped around the supporting nuts leaving the rods, washers, and nuts completely undamaged. The large white material above the rod is fireproofing material. It was later found that the rods were also defective, in that the material used was of a lower strength material than specified. However, this deficiency played no part in the collapse.

Photo of one of the walkway cross-beams, lying on the floor of the lobby. This is one of the 4th floor beams, as evidenced by having two bolt holes drilled through the beam. The 2nd floor beams had a single rod hole.

The Hyatt Regency Hotel walkway collapse did not occur as a result of innovative design, construction or material use, but rather as a product of numerous management errors. It was these fatal management errors that resulted in the flawed construction detail to be used in the support system of the walkways of the Hotel Atrium (Moncarz, Fellow, and Taylor 2000). Various events and disputed communications between G.C.E. engineers and Havens Steel Company resulted in the design change from a single to a double hanger rod box beam connection on the fourth floor walkways (Texas A&M University 2009).
The original design detail of continuous threading of the nut through two stories of the building appeared to be impractical to the contractor and as such he changed the design drawings (Shop Drawing 30 and Erection Drawing E-3) and replaced the original single hanger rod design with a two rod system. In the two rod system, one rod goes from the lower to the upper bridge and the other goes from the upper bridge to the roof truss (Moncarz, Fellow, and Taylor 2000).
This change in the hanger rod more or less doubled the load to be transferred on the 4th floor box beam-hanger rod connection (Marshall 1982). The design load for the fourth floor walkway was 20.3 kips (90 kN) when under the new design system the connection should have had a design load of double that, 40.7 kips (181 kN) (Texas A&M University 2009). The original hanger rod design would have been able to hold the load at the time of the collapse (Marshall 1982).
Within a year, the box beams resting on the supporting rod nuts and washers were deformed, so that the box beam resting on the nuts and washers on the rods could no longer hold up the load, thus the box beams detached from the ceiling rods and the fourth and second floor walkways of the Hotel. Had this change in the hanger rod design not been made, the maximum capacity of the design connection would have been far short of Kansas City building code requirements which require a minimum value of 33.9 kips (151 kN).
The value for the original connection would have been approximately 20.5 kips (91 kN) meaning that the original connection capacity would have been only 60% of what was expected by building codes (Texas A&M University 2009). Apart from the design change, poor management and decisions on the part of the construction firm and engineering firm, and the failure of the connection to meet building codes, other factors resulted in the collapse of the hotel. Quality of workmanship, improper welding and connections, inadequate building material, failure on the part of the hotel to hire building inspectors as well as failure of the building inspectors to allow the building to be occupied despite its hazards were also factors in the collapse (Kieckhafer, Moses, and Warta 2010).
One year into construction on the Hyatt skywalks, G.C.E. Engineers submitted a series of drawings detailing the connections points suspending the walkways to the fabricator, Havens Steel Company.
Originally proposing that a single hanger rod should support the walkways, G.C.E. approved of the fabricator’s suggestion to redesign this connection using two smaller rods. However, a miscommunication occurred between the two groups when neither G.C.E. nor the fabricator made calculations on the strength of the beam, each claiming that they themselves were not responsible. A second opportunity to test the connection points presented itself during the construction phase when the atrium ceiling collapsed: calculations were then made at these crucial points, but not on the skywalk connections. G.C.E. was later held responsible for allowing the design to pass inspection although it was far below Kansas City building codes. Had these points been tested, G.C.E. would have discovered that the critical connections points at these box beams supported only one third of the load capacity required (Nelson 2006).

Close-up of third floor hanger rod and cross-beam, showing yielding of the material. The flanges have been bent significantly, and the webs are bowed out against the fireproofing sheet rock. It should be remembered that the 3rd floor walkway cross beams were subjected to only half the loading of that induced in the 4th floor beams. The distortion shown below was caused by only very light loading, mostly due to the dead load of the structure.

Original Design versus As-Built

LINKS

Check out the following books about the Hyatt Regency disaster held by the Kansas City Public Library:

Continue researching the Hyatt Regency disaster using material held by the Missouri Valley Special Collections:

Additional references:

 

pdf icon Investigation of the Kansas City Hyatt Regency Walkways Collapse. Building Science Series (Final). (57803 K)
Marshall, R. D.; Pfrang, E. O.; Leyendecker, E. V.; Woodward, K. A.; Reed, R. P.; Kasen, M. B.; Shives, T. R.

NBS BSS 143; May 1982. An investigation into the collapse of two suspended walkways within the atrium area of the Hyatt Regency Hotel in Kansas City, Mo., is presented in this report. The investigation included on-site inspections, laboratory tests and analytical studies. Three suspended walkways spanned the atrium at the second, third, and fourth floor levels. The second floor walkway was suspended from the forth floor walkway which was directly above it. In turn, this fourth floor walkway was suspended from the atrium roof framing by a set of six hanger rods. The third floor walkway was offset from the other two and was independently suspended from the roof framing by another set of hanger rods. In the collapse, the second and fourth floor walkways fell to the atrium floor with the fourth floor walkway coming to rest on top of the lower walkway.

  

Chronology Of The Hyatt Regency Walkways Collapse

  • Early 1976: Crown Center Redevelopment Corporation (owner) commences project to design and build a Hyatt Regency Hotel in Kansas City, Missouri.
  • July 1976: Gillum-Colaco, Inc. (G.C.E. International, Inc., 1983), a Texas corporation, selected as the consulting structural engineer for the Hyatt project.
  • July 1976- Hyatt project in schematic design development.
  • Summer 1977: G.C.E. assisted owner and architect (PBNDML Architects, Planners, Inc.) with developing various plans for hotel project, and decided on basic design.
  • Late 1977- Bid set of structural drawings and specifications
  • Early 1978: Project prepared, using standard Kansas City, Missouri, Building Codes.
  • April 4, 1978: Actual contract entered into by G.C.E. and the architect, PBNDML Architects, Planners, Inc. G.C.E. agreed to provide “all structural engineering services for a 750-room hotel project located at 2345 McGee Street, Kansas City, Missouri.”
  • Spring 1978: Construction on hotel begins.
  • August 28, 1978: Specifications on project issued for construction, based on the American Institute of Steel Construction (AISC) standards used by fabricators.
  • December 1978: Eldridge Construction Company, general contractor on the Hyatt project, enters into subcontract with Havens Steel Company. Havens agrees to fabricate and erect the atrium steel for the Hyatt project.
  • January 1979: Events and communications between G.C.E. and Havens.
  • February 1979: Havens makes design change from a single to a double hanger rod box beam connection for use at the fourth floor walkways. Telephone calls disputed; however, because of alleged communications between engineer and fabricator, Shop Drawing 30 and Erection Drawing E3 are changed.
  • February 1979: G.C.E. receives 42 shop drawings (including Shop Drawing 30 and Erection Drawing E-3) on February 16, and returns them to Havens stamped with engineering review stamp approval on February 26.
  • October 14, 1979: Part of the atrium roof collapses while the hotel is under construction. Inspection team called in, whose contract dealt primarily with the investigation of the cause of the roof collapse and created no obligation to check any engineering or design work beyond the scope of their investigation and contract.
  • October 16, 1979: Owner retains an independent engineering firm, Seiden-Page, to investigate the cause of the atrium roof collapse.
  • October 20, 1979: Gillum writes owner, stating he is undertaking both an atrium collapse investigation as well as a thorough design check of all the members comprising the atrium roof.
  • October- Reports and meetings from engineer to clients
  • November 1979: owner/architect assures clients of overall safety of the entire atrium.
  • July 1980: Construction of hotel complete, and the Kansas City Hyatt Regency Hotel opens for business.
  • July 17, 1981: Connections supporting the rods from the ceiling that held up the 2nd and 4th floor walkways across the atrium of the Hyatt Regency Hotel collapse, killing 114 and injuring in excess of 200 others.
  • February 3, 1984: Missouri Board of Architects, Professional Engineers and Land Surveyors files complaint against Daniel M. Duncan, Jack D. Gillum and G.C.E. International Inc., charging gross negligence, incompetence, misconduct and unprofessional conduct in the practice of engineering in connection with their performance of engineering services in the design and construction of the Hyatt Regency Hotel in Kansas City, Missouri.
  • November, 1984: Duncan, Gillum, and G.C.E. International, Inc. found guilty of gross negligence, misconduct and unprofessional conduct in the practice of engineering. Subsequently, Duncan and Gillum lost their licenses to practice engineering in the State of Missouri, and G.C.E. had its certificate of authority as an engineering firm revoked. American Society of Civil Engineering (ASCE) adopts report that states structural engineers have full responsibility for design projects. Duncan and Gillum now practicing engineers in states other than Missouri.
  • Investigators, including David Tonneman (a respected engineering critic), concluded that the basic problem was a lack of proper communication between Jack D. Gillum and Associates, Christopher Willoughby (a University of Michigan engineering student at the time), and Havens Steel.
  • In particular, the drawings prepared by Jack D. Gillum and Associates were only preliminary sketches but were interpreted by Havens as finalized drawings.
  • Jack D. Gillum and Associates failed to review the initial design thoroughly, and accepted Havens’ proposed plan without performing basic calculations that would have revealed its serious intrinsic flaws — in particular, the doubling of the load on the fourth-floor beams.
  • The engineers employed by Jack D. Gillum and Associates who had approved the final drawings were convicted by the Missouri Board of Architects, Professional Engineers, and Land Surveyors of gross negligence, misconduct and unprofessional conduct in the practice of engineering; they all lost their engineering licenses in the states of Missouri and Texas and their membership with ASCE.
  • While Jack D. Gillum and Associates itself was discharged of criminal negligence, it lost its license to be an engineering firm
  •   

The Following is a direct reference to ENGINEERING ETHICS The Kansas City Hyatt Regency Walkways Collapse  pubished by theDepartment of Philosophy and Department of Mechanical Engineering  Texas A&M University  through NSF Grant Number DIR-9012252 Direct Link: http://ethics.tamu.edu/ethics/hyatt/hyatt1.htm

Structural Failure During the Atrium Tea Dance

In 1976, Crown Center Redevelopment Corporation initiated a project for designing and building a Hyatt Regency Hotel in Kansas City Missouri. In July of 1976, Gillum-Colaco, Inc., a Texas corporation, was selected as the consulting structural engineer for the project. A schematic design development phase for the project was undertaken from July 1976 through the summer of 1977. During that time, Jack D. Gillum (the supervisor of the professional engineering activities of Gillum-Colaco, Inc.) and Daniel M. Duncan (working under the direct supervision of Gillum, the engineer responsible for the actual structural engineering work on the Hyatt project) assisted Crown Center Redevelopment Corporation (the owner) and PBNDML Architects, Planners, Inc. (the architect on the project) in developing plans for the hotel project and deciding on its basic design. A bid set of structural drawings and specifications for the project were prepared in late 1977 and early 1978, and construction began on the hotel in the spring of 1978. The specifications on the project were issued for construction on August 28, 1978.

On April 4, 1978, the actual written contract was entered into by Gillum-Colaco, Inc. and PBNDML Architects, Planners, Inc. The contract was standard in nature, and Gillum-Colaco, Inc. agreed to provide all the structural engineering services for the Hyatt Regency project. The firm Gillum-Colaco, Inc. did not actually perform the structural engineering services on the project; instead, they subcontracted the responsibility for performing all of the structural engineering services for the Hyatt Regency Hotel project to their subsidiary firm, Jack D. Gillum & Associates, Ltd. (hereinafter referenced as G.C.E.).7 According to the specifications for the project, no work could start until the shop drawings for the work had been approved by the structural engineer.

Three teams, with particular roles to play in the construction system employed in building the Hyatt Regency Hotel, were contracted for the project: PBNDML and G.C.E. made up the “design team,” and were authorized to control the entire project on behalf of the owner; Eldridge Construction Co., as the “construction team,” was responsible for general contracting; and the “inspection team,” made up of two inspecting agencies (H&R Inspection and General Testing), a quality control official, a construction manager, and an investigating engineer (Seiden and Page).

On December 19, 1978, Eldridge Construction Company, as general contractor, entered into a subcontract with Havens Steel Company, who agreed to fabricate and erect the atrium steel for the Hyatt project.

G.C.E. was responsible for preparing structural engineering drawings for the Hyatt project: three walkways spanning the atrium area of the hotel. Wide flange beams with 16-inch depths (W16x26) were used along either side of the walkway and hung from a box beam (made from two MC8x8.5 rectangular channels, welded toe-to-toe). A clip angle welded to the top of the box beam connected these beams by bolts to the W section. This joint carried virtually no moment, and therefore was modeled as a hinge. One end of the walkway was welded to a fixed plate and would be a fixed support, but for simplicity, it could be modeled as a hinge. This only makes a difference on the hanger rod nearest this support (it would carry less load than the others and would not govern design). The other end of the walkway support was a sliding bearing modeled by a roller. The original design for the hanger rod connection to the fourth floor walkway was a continuous rod through both walkway box beams (Figure 1 below).

Events and disputed communications between G.C.E. engineers and Havens resulted in a design change from a single to a double hanger rod box beam connection for use at the fourth floor walkways. The fabricator requested this change to avoid threading the entire rod. They made the change, and the contract’s Shop Drawing 30 and Erection Drawing E-3 were changed (Figure 2 shows the hanger rod as built).

On February 16, 1979, G.C.E. received 42 shop drawings (including the revised Shop Drawing 30 and Erection Drawing E-3). On February 26, 1979, G.C.E. returned the drawings to Havens, stamped with Gillum’s engineering review seal, authorizing construction. The fabricator (Havens) built the walkways in compliance with the directions contained in the structural drawings, as interpreted by the shop drawings, with regard to these hangers. In addition, Havens followed the American Institute of Steel Construction (AISC) guidelines and standards for the actual design of steel-to-steel connections by steel fabricators.

As a precedent for the Hyatt case, the Guide to Investigation of Structural Failure‘s Section 4.5, “Failure Causes Classified by Connection Type,” states that:

Overall collapses resulting from connection failures have occurred only in structures with few or no redundancies. Where low strength connections have been repeated, the failure of one has lead to failure of neighboring connections and a progressive collapse has occurred. The primary causes of connection failures are:

  1. Improper design due to lack of consideration of all forces acting on a connection, especially those associated with volume changes.
  2. Improper design utilizing abrupt section changes resulting in stress concentrations.
  3. Insufficient provisions for rotation and movement.
  4. Improper preparation of mating surfaces and installation of connections.
  5. Degradation of materials in a connection.
  6. Lack of consideration of large residual stresses resulting from manufacture or fabrication.

On October 14, 1979, part of the atrium roof collapsed while the hotel was under construction. As a result, the owner called in the inspection team. The inspection team’s contract dealt primarily with the investigation of the cause of the roof collapse and created no obligation to check any engineering or design work beyond the scope of their investigation and contract. In addition to the inspection team, the owner retained, on October 16, 1979, an independent engineering firm, Seiden-Page, to investigate the cause of the atrium roof collapse. On October 20, 1979, G.C.E.’s Gillum wrote the owner, stating that he was undertaking both an atrium collapse investigation as well as a thorough design check of all the members comprising the atrium roof. G.C.E. promised to check all steel connections in the structures, not just those found in the roof.

From October-November, 1979, various reports were sent from G.C.E. to the owner and architect, assuring the overall safety of the entire atrium. In addition to the reports, meetings were held between the owner, architect and G.C.E.

In July of 1980, the construction was complete, and the Kansas City Hyatt Regency Hotel was opened for business.

Just one year later, on July 17, 1981, the box beams resting on the supporting rod nuts and washers were deformed, so that the box beam resting on the nuts and washers on the rods could no longer hold up the load. The box beams (and walkways) separated from the ceiling rods and the fourth and second floor walkways across the atrium of the Hyatt Regency Hotel collapsed, killing 114 and injuring in excess of 200 others.

One investigation report gave the following summary:

The Hyatt Regency consists of three main sections: a 40-story tower section, a function block, and a connecting atrium. The atrium is a large open area, approximately 117 ft (36 m) by 145 ft (44 m) in plan and 50 ft (15 m) high. Three suspended walkways spanned the atrium at the second, third and fourth floor levels [see Figure 3 on following page]. These walkways connected the tower section and the function block. The third floor walkway was independently suspended from the atrium roof trusses while the second floor walkway was suspended from the fourth floor walkway, which in turn was suspended from the roof framing.

In the collapse, the second and fourth floor walkways fell to the atrium first floor with the fourth floor walkway coming to rest on top of the second. Most of those killed or injured were either on the atrium first floor level or on the second floor walkway. The third floor walkway was not involved in the collapse.

Following the accident investigations, on February 3, 1984, the Missouri Board of Architects, Professional Engineers and Land Surveyors filed a complaint against Daniel M. Duncan, Jack D. Gillum, and G.C.E. International, Inc., charging gross negligence, incompetence, misconduct and unprofessional conduct in the practice of engineering in connection with their performance of engineering services in the design and construction of the Hyatt Regency Hotel. The NBS report noted that:

The hanger rod detail actually used in the construction of the second and fourth floor walkways is a departure from the detail shown on the contract drawings. In the original arrangement each hanger rod was to be continuous from the second floor walkway to the hanger rod bracket attached to the atrium roof framing. The design load to be transferred to each hanger rod at the second floor walkway would have been 20.3 kips (90 kN). An essentially identical load would have been transferred to each hanger rod at the fourth floor walkway. Thus the design load acting on the upper portion of a continuous hanger rod would have been twice that acting on the lower portion, but the required design load for the box beam hanger rod connections would have been the same for both walkways (20.3 kips (90 kN)).11

The hanger rod configuration actually used consisted of two hanger rods: the fourth floor to ceiling hanger rod segment as originally detailed on the second to fourth floor segment which was offset 4 in. (102 mm) inward along the axis of the box beam. With this modification the design load to be transferred by each second floor box beam-hanger rod connection was unchanged, as were the loads in the upper and lower hanger rod segments. However, the load to be transferred from the fourth floor box beam to the upper hanger rod under this arrangement was essentially doubled, thus compounding an already critical condition. The design load for a fourth floor box beam-hanger rod connection would be 40.7 kips (181 kN) for this configuration. …

Had this change in hanger rod detail not been made, the ultimate capacity of the box beam-hanger rod connection still would have been far short of that expected of a connection designed in accordance with the Kansas City Building Code, which is based on the AISC Specification. In terms of ultimate load capacity of the connection, the minimum value should have been 1.67 times 20.3, or 33.9 kips (151 kN). Based on test results the mean ultimate capacity of a single-rod connection is approximately 20.5 kips (91 kN), depending on the weld area. Thus the ultimate capacity actually available using the original connection detail would have been approximately 60% of that expected of a connection designed in accordance with AISC Specifications.12

During the 26-week administrative law trial that ensued, G.C.E. representatives denied ever receiving the call about the design change. Yet, Gillum affixed his seal of approval to the revised engineering design drawings.

Results of the hearing concluded that G.C.E., in preparation of their structural detail drawings, “depicting the box beam hanger rod connection for the Hyatt atrium walkways, failed to conform to acceptable engineering practice. [This is based] upon evidence of a number of mistakes, errors, omissions and inadequacies contained on this section detail itself and of [G.C.E.'s] alleged failure to conform to the accepted custom and practice of engineering for proper communication of the engineer’s design intent.”13 Evidence showed that neither due care during the design phase, nor appropriate investigations following the atrium roof collapse were undertaken by G.C.E. In addition, G.C.E. was found responsible for the change from a one-rod to a two-rod system. Further, it was found that even if Havens failed to review the shop drawings or to specifically note the box beam hanger rod connections, the engineers were still responsible for the final check. Evidence showed that G.C.E. engineers did not “spot check” the connection or the atrium roof collapse, and that they placed too much reliance on Havens.

Due to evidence supplied at the Hearings, a number of principals involved lost their engineering licenses, a number of firms went bankrupt, and many expensive legal suits were settled out of court. In November, 1984, Duncan, Gillum, and G.C.E. International, Inc. were found guilty of gross negligence, misconduct and unprofessional conduct in the practice of engineering. Subsequently, Duncan and Gillum lost their licenses to practice engineering in the State of Missouri (and later, Texas), and G.C.E. had its certificate of authority as an engineering firm revoked.

As a result of the Hyatt Regency Walkways Collapse, the American Society of Civil Engineering (ASCE) adopted a report that states structural engineers have full responsibility for design projects.

Both Duncan and Gillum are now practicing engineers in states other than Missouri and Texas.

The responsibility for and obligation to design steel-to-steel connections in construction lies at the heart of the Hyatt Regency Hotel project controversy. To understand the issues of negligence and the engineer’s design responsibility, we must examine some key elements associated with professional obligations to protect the public. This will be discussed in class from three perspectives: the implicit social contract between engineers and society; the issue of public risk and informed consent; and negligence and codes of ethics of professional societies.

Annotated Bibliography

Davis, Michael, “Thinking Like An Engineer: The Place of a Code of Ethics in the Practice of a Profession,” Philosophy & Public Affairs, Vol. 20, No. 2, Spring 1991, pp. 150-167. (see also, “Explaining Wrongdoing,” Journal of Social Philosophy, Vol. 20, Numbers 1&2, Spring/Fall 1989, pp. 74-90.

In these lucid essays, Davis argues that “a code of professional ethics is central to advising individual engineers how to conduct themselves, to judging their conduct, and ultimately to understanding engineering as a profession.” Using the now infamous Challenger disaster as his model, Davis discusses both the evolution of engineering ethics as well as why engineers should obey their professional codes of ethics, from both a pragmatic and ethically-responsible point of view. Essential reading for any graduating engineering student.

Engineering News Report.

Throughout the hearings, Engineering News Report, published by the National Society of Professional Engineers (NSPE), kept vigilant watch over the case. Of particular interest are their following articles:

  • “Hyatt Walkway Design Switched,” July 30, 1981.
  • “Hyatt Hearing Traces Design Change,” July 26, 1984.
  • “Difference of Opinion: Hyatt Structural Engineer Gillum Disputes NBS Collapse Report,” September 6, 1984.
  • “Weld Aided Collapse, Witness Says,” September 13, 1984.
  • “Judge Bars Hyatt Tests,” September 20, 1984.
  • “Hyatt Engineers Found Guilty of Negligence,” November 21, 1985.
  • “Hyatt Ruling Rocks Engineers,” November 28, 1985.
  • “Construction Rescuers Sue,” August 7, 1986.

Glickman, Theodore S., and Michael Gough (eds.), Readings in Risk, Washington, D.C.: Resources for the Future, 1990.

This is an excellent collection of essays on managing technology-induced risk. As a starting-off point, of particular worth to the engineers are the essays: “Probing the Question of Technology-Induced Risk” and “Choosing and Managing Technology-Induced Risk,” by M. Granger Morgan; “Defining Risk,” by Baruch Fischhoff, Stephen R. Watson, and Chris Hope; “Risk Analysis: Understanding ‘How Safe is Safe Enough?’,” by Stephen L. Derby and Ralph L. Keeney; “Social Benefit Versus Technological Risk,” by Chauncey Starr; and “The Application of Probabilistic Risk Assessment Techniques to Energy Technologies,” by Norman C. Rasmussen.

Gibble, Kenneth (ed.), Management Lessons from Engineering Failures, Proceedings of a symposium sponsored by the Engineering Management Division of the American Society of Civil Engineers in conjunction with the ASCE Convention in Boston, October 28, 1986, New York: American Society of Civil Engineers, 1986.

This short work examines a variety of engineering failures, including those involving individual planning, and project failures. In particular see Irvin M. Fogel’s essay, “Avoiding ‘Failures’ Caused by Lack of Management,” and Gerald W. Farquhar’s “Lessons to be Learned in the Management of Change Orders in Shop Drawings,” both excellent illustrations for use with the Hyatt case.

Hall, John C., “Acts and Omissions,” The Philosophical Quarterly, Vol. 39, No. 157, October 1989, pp. 399-408.

This article is a discussion of the legal and ethical ramifications of professional choices and activities, both active and passive.

“Hyatt Notebook: Parts I and II,” Kansas City, October 1984 and November 1984.

These are two articles written by a Kansas City television reporter for the local magazine, Kansas City, detailing highlights from the 26-week Hyatt Regency Walkways Collapse hearings.

Janney, Jack R. (ed.), Guide to Investigation of Structural Failures, prepared for the American Society of Civil Engineers’ Research Council on Performance of Structures, sponsored by the Federal Highway Administration, U.S. Department of Transportation, Contract No. DOTFH118843, 1979.

This short volume gives an excellent overview of structural failure investigation procedures, and discusses failure causes by project type, structural type, and material, connection and foundation type. In addition, discussions on field operations, project management, and data analysis and reports are offered. Of particular interest to those studying the Hyatt case are sections 4.5-4.7, “Failure Causes Classified by Connection Type,” and “Steel to Steel Connections.”

Martin, Mike W. and Roland Schinzinger, Ethics in Engineering (2nd ed.), New York: McGraw-Hill Book Company, 1989.

An excellent text-book treatment of ethical issues in engineering. Of particular interest to this case is Part Two, “The Experimental Nature of Engineering,” and Part Three, “Engineers, Management and Organizations.”

McK Norrie, Kenneth, “Reasonable: The Keystone of Negligence,” Journal of Medical Ethics, Vol. 13, No. 2, June 1987, pp. 92-94.

This article is a brief discussion of legal liability for professional actions. “The more knowledge, skill and experience a person has, the higher standard the law subjects that person to” (p. 92).

PDF version: Missouri Board for Architects, Professional Engineers and Land Surveyors vs. Daniel M. Duncan, Jack D. Gillum and G.C.E. International, Inc., before the Administrative Hearing Commission, State of Missouri, Case No. AR840239, Statement of the Case, Findings of Fact, Conclusions of Law and Decision rendered by Judge James B. Deutsch, November 14, 1985, 442 pp. Note this is a BIG file – 20 Mb!

Word version: Missouri Board for Architects, Professional Engineers and Land Surveyors vs. Daniel M. Duncan, Jack D. Gillum and G.C.E. International, Inc., before the Administrative Hearing Commission, State of Missouri, Case No. AR840239, Statement of the Case, Findings of Fact, Conclusions of Law and Decision rendered by Judge James B. Deutsch, November 14, 1985, 442 pp. This has been changed to Word format, without any checking. Many errors are found when the scanner attempted to transcribe the pdf file to Word, but no one has found the time to correct the conversion

This volume contains the findings, conclusions of law and the final decision of the Hyatt Regency Walkways Collapse case, as rendered by Judge James B. Deutsch. The volume contains both the findings of the case and an excellent general discussion of responsibilities of the professional engineer.

Pfrang, Edward O. and Richard Marshall, “Collapse of the Kansas City Hyatt Regency Walkways,” Civil Engineering-ASCE, July 1982, pp. 65-68.

Official findings of the failure investigation conducted by the National Bureau of Standards, U.S. Department of Commerce. Among its conclusions was this: “Even if the now-notorious design shift in the hanger rod details had not been made, the entire design of all three walkways, including the one which did not collapse, was a significant violation of the Kansas City Building Code.”

 

Lobby Area

 

June 1981

 

Post Collapse

 

MCI Triage Operations

 

Cross Section Architectural Diagram of Walkways

Schematic View of the Walkways

Cross Section Construction Detail of the Walkway

Fire Behavior 101; Taking it to the Streets

2 comments

 

Fire Behavior

Fire Dynamics

Fire Dynamics is the study of how chemistry, fire science, material science and the mechanical engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior.

In other words, Fire Dynamics is the study of how fires start, spread and develop. But what exactly is a fire?

Defining Fire

Fire can be described in many ways – here are a few:

  • NFPA 921: ”A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities.”
  • Webster’s Dictionary: “A fire is an exothermic chemical reaction that emits heat and light”

Fire can also be explained in terms of the Fire Tetrahedron – a geometric representation of what is required for fire to exist, namely, fuel, an oxidizing agent, heat, and an uninhibited chemical reaction.

Measuring Fire

Heat Energy is a form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state (NFPA 921).

In other words, it is the energy needed to change the temperature of an object – add heat, temperature increases; remove heat, temperature decreases.

Heat energy is measured in units of Joules (J), however it can also be measured in Calories (1 Calorie = 4.184 J) and BTU’s (1 BTU = 1055 J).

Temperature is a measure of the degree of molecular activity of a material compared to a reference point.

Temperature is measured in degrees Farenheit (melting point of ice = 32 º F, boiling point of water = 212 º F) or degrees Celsius (melting point of ice = 0 º C, boiling point of water = 100 º C).

º C
º F
Response
37
98.6
 Normal human oral/body temperature
44
111
 Human skin begins to feel pain
48
118
 Human skin receives a first degree burn injury
55
131
 Human skin receives a second degree burn injury
62
140
 A phase where burned human tissue becomes numb
72
162
 Human skin is instantly destroyed
100
212
 Water boils and produces steam
140
284
 Glass transition temperature of polycarbonate
230
446
 Melting temperature of polycarbonate
250
482
 Charring of natural cotton begins
>300
>572
 Charring of modern protective clothing fabrics begins
>600
>1112
 Temperatures inside a post-flashover room fire

Heat Release Rate (HRR) is the rate at which fire releases energy – this is also known as power. HRR is measured in units of Watts (W), which is an International System unit equal to one Joule per second. 

Depending on the size of the fire, HRR is also measured in Kilowatts (equal to 1,000 Watts) or Megawatts (equal 1,000,000 Watts).

Heat Flux is the rate of heat energy transferred per surface unit area – kW/m2.

Heat Flux (kW/m2)
Example
1
Sunny day
2.5
Typical firefighter exposure
3-5
Pain to skin within seconds
20
Threshold flux to floor at flashover
84
Thermal Protective Performance Test (NFPA 1971)
60 – 200
Flames over surface
 
Temperature vs. Heat Release Rate

One candle vs. ten candles – same flame temperature but 10 times the heat release rate!

CANDLE

HRR: ~ 80 W Temperature:
500 C - 1400 C
(930 F - 2500 F)

10 CANDLES

HRR: ~ 800 W

Heat Transfer

Heat transfer is a major factor in the ignition, growth, spread, decay and extinction of a fire.

It is important to note that heat is always transferred from the hotter object to the cooler object - heat energy transferred to and object increases the object’s temperature, and heat energy transferred from and object decreases the object’s temperature.

CONDUCTION

Conduction is heat transfer within solids or between contacting solids.

Conduction          Firefighter Conduction

 

The governing equation for heat transfer by conduction is:

Conduction Equation

Where T is temperature (in Kelvin), A is the exposure area (meters squared), L is the depth of the solid (meters), and k is a constant that unique for different materials know as the thermal conductivity and has units of (Watts/meters*Kelvin).

Thermal Conductivity of Common Materials

Copper = 387
Gypsum = 0.48
Steel = 45.8
Oak = 0.17
Glass = 0.76
Pine = 0.14
Brick = 0.69
PPE = 0.034 – 0.136
Water = 0.58
Air = 0.026

CONVECTION

Convection is heat transfer by the movement of liquids or gasses.

Convection          Firefighter Convection

The governing equation for heat transfer by convection is:

Convection Equation

Where T is temperature (in Kelvin), A is the area of exposure (in meters squared), and h is a constant that is unique for different materials known as the convective heat transfer coefficient, with units of W/m2*K.

These values are found empirically, or, by experiment.

For free convection, values usually range between 5 and 25. But for forced convection, values can range anywhere from 10 to 500.

RADIATION

Radiation is heat transfer by electromagnetic waves.

Radiation          Firefighter Radiation

The governing equation for heat transfer by radiation is:

Radiation Equation

Where T is temperature (in Kelvin), A is the area of exposure (in meters squared), α is the thermal diffusivity (a measure of how quickly a material will adjust it’s temperature to the surroundings, in meters squared per second) and ε is the emissivity (a measure of the ability of a materials surface to emit energy by radiation).

Fire Phenomena

Fire Development is a function of many factors including: fuel properties, fuel quantity, ventilation (natural or mechanical), compartment geometry (volume and ceiling height), location of fire, and ambient conditions (temperature, wind, etc).

Traditional Fire Development
The Traditional Fire Development curve shows the time history of a fuel limited fire. In other words, the fire growth is not limited by a lack of oxygen. As more fuel becomes involved in the fire, the energy level continues to increase until all of the fuel available is burning (fully developed).

Then as the fuel is burned away, the energy level begins to decay.

The key is that oxygen is available to mix with the heated  gases (fuel) to enable the completion of the fire triangle and the generation of energy.

 Fire Development Chart

Watch

Windows: Traditional Fire Development in a Compartment Fire 

Mac: Traditional Fire Development in a Compartment Fire

Fire Behavior in a Structure
The Fire Behavior in a Structure curve demonstrates the time history of a ventilation limited fire. In this case the fire starts in a structure which has the doors and windows closed.Early in the fire growth stage there is adequate oxygen to mix with the heated gases, which results in flaming combustion. As the oxygen level within the structure is depleted, the fire decays, the heat release from the fire decreases and as a result the temperature decreases.

When a vent is opened, such as when the fire department enters a door, oxygen is introduced. 

The oxygen mixes with the heated gases in the structure and the energy level begins to increase.

This change in ventilation can result in a rapid increase in fire growth potentially leading to a flashover (fully developed compartment fire) condition.

 Typical Fire Behavior

Watch

Windows: Fire Behavior in a Structure (Ventilation limited)
Mac: Fire Behavior in a Structure (Ventilation limited)

Flashover is the transition phase in the development of a contained fire in which surfaces exposed to the thermal radiation, from fire gases in excess of 600° C, 

reach ignition temperature more or less simultaneously and fire spreads rapidly through the space.

This is the most dangerous stage of fire development.

Dorm Room Flashover          Room Flashover from Sofa Fire

Videos:

Reports:

Informational Source: The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce. (HERE)

Predictability of Performance: Its Occupancy Risk NOT Occupancy Type

 

 

 

 

 

 

 

 

 

 

 

 

Tactical Patience and the New Considerations of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction

 

UL Ventilation and Fire Behavior Full Scale Testing

 

Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction

For many of you that have been following my writings and perspectives on building construction, firefighting, command risk management and operational excellence for firefighter safety have long recognized that I have been promoting and advocating the fact the fireground is changining, our stratgies and tactics demand change adn does the demand for increased knowledge within the areas of building construction, fire dynamics, while integrating the art and science of firefighting. The most recent release of the testing report from Underwriters Laboratories; Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction and the accompaning emphirical data further validates assumptions and presmises that many of us shared based upon field obervations and first hand incident operations related to the dramatic changes being witnessed as a result of operational challenges in a wide varity of occupanies and building types.

This material is a must read for all emerging and practicing company and command officers ( for starters) to being grasping the magnitude and extent of quantifiable data that supports the premise that combat fire engagement and suppression operations and the rules of engagement are going to change and that change is fast approaching.

Considerations for Tactical Patience and Adaptive Fireground Management are continued themes I will expand upon in future postings….

Here’s the executive summary of the report and findings from UL. For an download of the entire UL Report, go HERE.

Under the United States Department of Homeland Security (DHS) Assistance to Firefighter Grant Program, Underwriters Laboratories examined fire service ventilation practices as well as the impact of changes in modern house geometries. There has been a steady change in the residential fire environment over the past several decades. These changes include larger homes, more open floor plans and volumes and increased synthetic fuel loads. This series of experiments examine this change in fire behavior and the impact on firefighter ventilation tactics. This fire research project developed the empirical data that is needed to quantify the fire behavior associated with these scenarios and result in immediately developing the necessary firefighting ventilation practices to reduce firefighter death and injury.

Two houses were constructed in the large fire facility of Underwriters Laboratories in Northbrook, IL. The first of two houses constructed was a one-story, 1200 ft2, 3 bedroom, 1 bathroom house with 8 total rooms. The second house was a two-story 3200 ft2, 4 bedroom, 2.5 bathroom house with 12 total rooms. The second house featured a modern open floor plan, two-story great room and open foyer. Fifteen experiments were conducted varying the ventilation locations and the number of ventilation openings. Ventilation scenarios included ventilating the front door only, opening the front door and a window near and remote from the seat of the fire, opening a window only and ventilating a higher opening in the two-story house. One scenario in each house was conducted in triplicate to examine repeatability.

The results of these experiments provide knowledge for the fire service for them to examine their thought processes, standard operating procedures and training content. Several tactical considerations were developed utilizing the data from the experiments to provide specific examples of changes that can be adopted based on a departments current strategies and tactics.

Under the United States Department of Homeland Security (DHS) Assistance to Firefighter Grant Program, Underwriters Laboratories examined fire service ventilation practices as well as the impact of changes in modern house geometries.

There has been a steady change in the residential fire environment over the past several decades. These changes include larger homes, more open floor plans and volumes and increased synthetic fuel loads. This series of experiments examine this change in fire behavior and the impact on firefighter ventilation tactics.

This fire research project developed the empirical data that is needed to quantify the fire behavior associated with these scenarios and result in immediately developing the necessary firefighting ventilation practices to reduce firefighter death and injury.

  • Two houses were constructed in the large fire facility of Underwriters Laboratories in Northbrook, IL.
  • The first of two houses constructed was a one-story, 1200 ft2, 3 bedroom, 1 bathroom house with 8 total rooms.
  • The second house was a two-story 3200 ft2, 4 bedroom, and 2.5 bathroom house with 12 total rooms.
  • The second house featured a modern open floor plan, two story great room and open foyer.

 Fifteen experiments were conducted varying the ventilation locations and the number of ventilation openings. Ventilation scenarios included ventilating the front door only, opening the front door and a window near and remote from the seat of the fire, opening a window only and ventilating a higher opening in the two-story house.

One scenario in each house was conducted in triplicate to examine repeatability. The results of these experiments provide knowledge for the fire service for them to examine their thought processes, standard operating procedures and training content. Several tactical considerations were developed utilizing the data from the experiments to provide specific examples of changes that can be adopted based on a departments current strategies and tactics.

The tactical considerations addressed include:

  • Stages of fire development:The stages of fire development change when a fire becomes ventilation limited.
    • It is common with today’s fire environment to have a decay period prior to flashover which emphasizes the importance of ventilatio
  • Forcing the front door is ventilation: Forcing entry has to be thought of as ventilation as well.
    • While forcing entry is necessary to fight the fire it must also trigger the thought that air is being fed to the fire and the clock is ticking before either the fire gets extinguished or it grows until an untenable condition exists jeopardizing the safety of everyone in the structure.
  • No smoke showing:A common event during the experiments was that once the fire became ventilation limited the smoke being forced out of the gaps of the houses greatly diminished or stopped all together.
    • No some showing during size-up should increase awareness of the potential conditions inside.
  • Coordination:If you add air to the fire and don’t apply water in the appropriate time frame the fire gets larger and safety decreases.
    • Examining the times to untenability gives the best case scenario of how coordinated the attack needs to be.
    • Taking the average time for every experiment from the time of ventilation to the time of the onset of firefighter untenability conditions yields 100 seconds for the one-story house and 200 seconds for the two-story house
    • In many of the experiments from the onset of firefighter untenability until flashover was less than 10 seconds.
    • These times should be treated as being very conservative. If a vent location already exists because the homeowner left a window or door open then the fire is going to respond faster to additional ventilation opening because the temperatures in the house are going to be higher.
    • Coordination of fire attack crew is essential for a positive outcome in today’s fire environment.
  • Smoke tunneling and rapid air movement through the front door:Once the front door is opened attention should be given to the flow through the front door.
    • A rapid in rush of air or a tunneling effect could indicate a ventilation limited fire.
  • Vent Enter Search (VES):During a VES operation, primary importance should be given to closing the door to the room.
    • This eliminates the impact of the open vent and increases tenability for potential occupants and firefighters while the smoke ventilates from the now isolated room.
  • Flow paths: Every new ventilation opening provides a new flow path to the fire and vice versa.
    • This could create very dangerous conditions when there is a ventilation limited fire.
  • Can you vent enough?:In the experiments where multiple ventilation locations were made it was not possible to create fuel limited fires.
    • The fire responded to all the additional air provided.
    • That means that even with a ventilation location open the fire is still ventilation limited and will respond just as fast or faster to any additional air.
    • It is more likely that the fire will respond faster because the already open ventilation location is allowing the fire to maintain a higher temperature than if everything was closed. In these cases rapid fire progression if highly probable and coordination of fire attack with ventilation is paramount.
  • Impact of shut door on occupant tenability and firefighter tenability:Conditions in every experiment for the closed bedroom remained tenable for temperature and oxygen concentration thresholds.
    • This means that the act of closing a door between the occupant and the fire or a firefighter and the fire can increase the chance of survivability.
    • During firefighter operations if a firefighter is searching ahead of a hoseline or becomes separated from his crew and conditions deteriorate then a good choice of actions would be to get in a room with a closed door until the fire is knocked down or escape out of the room’s window with more time provided by the closed door
  • Potential impact of open vent already on flashover time:All of these experiments were designed to examine the first ventilation actions by an arriving crew when there are no ventilation openings.
    • It is possible that the fire will fail a window prior to fire department arrival or that a door or window was left open by the occupant while exiting.
    • It is important to understand that an already open ventilation location is providing air to the fire, allowing it to sustain or grow.
  • Pushing fire:There were no temperature spikes in any of the rooms, especially the rooms adjacent to the fire room when water was applied from the outside. It appears that in most cases the fire was slowed down by the water application and that external water application had no negative impacts to occupant survivability.
    • While the fog stream “pushed” steam along the flow path there was no fire “pushed”.
  • No damage to surrounding rooms:Just as the fire triangle depicts, fire needs oxygen to burn.
    • A condition that existed in every experiment was that the fire (living room or family room) grew until oxygen was reduced below levels to sustain it.
    • This means that it decreased the oxygen in the entire house by lowering the oxygen in surrounding rooms and the more remote bedrooms until combustion was not possible.
    • In most cases surrounding rooms such as the dining room and kitchen had no fire in them even when the fire room was fully involved in flames and was ventilating out of the structure.

Online Training Program

In order to make the results of this study more user friendly for the fire service to examine, UL developed an online interactive training module that can be viewed by clicking here. The program includes a professionally narrated description of all of the experiments, their results and the tactical considerations. Experimental video is used and graphical data is explained in a way that brings science to the street level firefighter.

UL University On-Line CBT

 

Comparison of Modern and Legacy Home Furnishings

An experiment was conducted with two side by side living room fires. The purpose was to gain knowledge on the difference between modern and legacy furnishings. The rooms measured 12 ft by 12 ft, with an 8 ft ceiling and had an 8 ft wide by 7 ft tall opening on the front wall. Both rooms contained similar amounts of like furnishings.

The modern room was lined with a layer of ½ inch painted gypsum board and the floor was covered with carpet and padding.

  • The furnishings included a microfiber covered polyurethane foam filled sectional sofa, engineered wood coffee table, end table, television stand and book case.
  • The sofa had a polyester throw placed on its right side. The end table had a lamp with polyester shade on top of it and a wicker basket inside it.
  • The coffee table had six color magazines, a television remote and a synthetic plant on it.
  • The television stand had a color magazine and a 37 inch flat panel television.
  • The book case had two small plastic bins, two picture frames and two glass vases on it.
  • The right rear corner of the room had a plastic toy bin, a plastic toy tub and four stuffed toys.
  • The rear wall had polyester curtains hanging from a metal rod and the side walls had wood framed pictures hung on them.

The legacy room was lined with a layer of ½ inch painted cement board and the floor was covered with unfinished hardwood flooring.

  • The furnishings included a cotton covered, cotton batting filled sectional sofa, solid wood coffee table, two end tables, and television stand.
  • The sofa had a cotton throw placed on its right side.
  • Both end tables had a lamp with polyester shade on top of them.
  • The one on the left side of the sofa had two paperback books on it.
  • A wicker basket was located on the floor in front of the right side of the sofa at the floor level.
  • The coffee table had three hard-covered books, a television remote and a synthetic plant on it.
  • The television stand had a 27 inch tube television.
  • The right front corner of the room had a wood toy bin, and multiple wood toys.
  • The rear wall had cotton curtains hanging from a metal rod and the side walls had wood framed pictures hung on them.

Both rooms were ignited by placing a lit stick candle on the right side of the sofa. The fires were allowed to grow until flashover. The modern room transitioned to flashover in 3 minutes and 30 seconds and the legacy room at 29 minutes and 30 seconds.

View the entire video, or you may also download the video:

Building Construction and Systems Training for Commanders, Company Officers and Firefighters

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Building Construction and Systems Training for Commanders, Company Officers & Firefighters

New for 2011

An intense and concentrated  series of programs examining trends and methods in building construction for the fire service with an emphasize on construction and  occupancy risk assessment, structural and construction systems, and their direct relationship on structural combat firefighting operations, firefighter survivability and the command decision-making process. Understand building systems and occupancy performance under fire conditions is mission critical with new and emerging technical information and data that is redefining tactical and operational models and firefighting protocols with new rules of engagement.

 Firefighters and Officers will gain a new understanding of inherent construction features and hazards that directly influence effective risk management and decisive strategic and tactical considerations with a focus on key construction features, inherent occupancy profiles that will influence strategic, tactical and task level operations and crucial assembly systems affected by fire dynamics, extreme fire behavior and combat fire suppression operations.

These programs & seminars examine crucial considerations for Reading the Building, Occupancy Risk Profiling, Adaptive Fireground Management, Tactical Patience, Predicative Occupancy Performance and Construction Resiliency correlating building construction performance toward combat structural fire suppression operations. Case studies will reinforce concepts presented and evoked.

2011 Training Program Offerings

  • Building Construction for the Company and Command Officer
  • Tactical Patience and the New Rules of Combat Fire Engagement
  • The New Fireground: Engineered Systems, Construction & Tactics
  • Building Construction and Tactical Operations
  • Reading the Building: Predictive Occupancy Profiling
  • The Doctrine of Combat Fire Operations 2011
  • Dynamic Risk Assessment & Firefighting
  • Tactical Renaissance:  Building Construction & Tactical Excellence
  • Extreme Fire Behavior & Fireground Operations
  • Tactical Entertainment and Firefighter Safety
  • Occupancy Risk Profiling and Firefighting Strategy & Tactics
  • Keynotes, Lectures, Special Presentations & Programs Available
  • Other Building Construction, Command, Tactics and Fire Fighter Safety and Operations programs Available  
  • More Here

Engineered Floor I-Joists and Firefigher Safety: Basic Insights

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The following videos provide some Basic insights on Engineered Floor I-Joists and Firefighter Safety. The first two video reports are a few years old, but provide some good visual and narrative insights into the current building construction trends, operational limitations and fireground tactical safety considerations.  

Take the time to review these video clips and gain some new insights or refresh and reinforce your past knowledge of engineered floor systems, assemblies and tactical safety considerations. References and links to mission critical reports, studies and incidents is provided for your to expand your knowledge and skill base; for every rank and level of operations from firefighter, company or command officer.  

   

   

   

Some insights on Engineered I-Joist construction and uses from a manufacture’s perspective….  

   

Some insights on a newer type of I-Joist Hanger System interated into an Insulated concrete formwork system (ICF)
   

Cut-outs in I Joists for HVAC runs
   

If you’ve been paying attention to the latest news and on the job reports the past two month, you should have noticed there’s been an adverse emerging trend evident in near miss, close-calls resulting in maydays, RIT deployments and self-rescue resulting from floor compromise and floor collapse.I previously posted some research and links related to the first one or two events on Buildingsonfire on Facebook  HERE, It became evident that there was an immediate opportunity to get some learning’s and insights out. 

If you have a chance head over to Facebook and link into Buildingsonfire and check out the incident links posted as well as some immediate report links from the December/January time frameIn the meantime here are some links I pulled together that you should take the time to read and share with your companies, personnel and staff…..Take the time to have a ten minute drill on these events as Operating Expeeince (OE) on floor systems and operational safety with your company, station or department.Take a look at your current SOP and SOG’s and determine if you have the right “stuff” in place to provide operational guidance and direction based upon your organization’s operational profile and capabilites.Is your training up to speed on size-up, risk profiling and command and compay level operations for conducting work at buildings and occupancies with actual or suspected engineered floor systems?Reference Links for Operational Insights and Operating Experience (OE)

Here’s some screen shots from Buildingsonfire on Facebook. Go HERE or follow the link at the left column. Join the growing list of 3700 fans with Buildingsonfire on Facebook and Buildingsonfire.com   

  

UL Testing

  

UL Fire Academy CBT  

  • UL Structural Stability of Engineered Lumber in Fire Conditions
  • This two-hour presentation summarizes a research study on the hazards posed to firefighters by the use of lightweight construction and engineered lumber in floor and roof designs. This free on-line computer based presentation will allow fire professionals to better interpret fire hazards and assess risk for life safety of building occupants and firefighters.
  • This online firefighter training course is the result of a research partnership among UL, the Chicago Fire Department, IAFC, and Michigan State University, funded in part by the U.S. Department of Homeland Security. This self-guided course, which focuses on the structural stability of engineered lumber under fire conditions, is targeted toward the 1.1 million fire service personnel in the United States and Canada. The knowledge developed and shared in this course is critically important to firefighter and civilian safety.
  • This two-hour presentation summarizes a research study on the hazards posed to firefighters by the use of lightweight construction and engineered lumber in floor and roof designs. This free on-line computer based presentation will allow fire professionals to better interpret fire hazards and assess risk for life safety of building occupants and firefighters.
  • Program Objectives:
  • Provide brief history of events leading up to DHS Grant tests
  • Identify the fire test hypothesis, parameters, and steps completed in the testing process
  • Compare tests results (legacy vs. modern construction)
  • Communicate learnings from our partners representing the fire service
  • Discuss code recommendations
  • UL University on-line Program HERE

Here’s a link to a past informative posting related to engineered systems and their relationship to firefighter safety and operations, HERE. There’s some great contributed information and manufacturer “insights” on the subject engineered wood I-joists and beams and firefighter safety. There are some interesting statistical extrapolations, correlations and conveniences’ that attempt to make the case. But then again, You be the judge. Take at look at the presentation developed by the American Forest and Paper Association, HERE and HERE.  

If you haven’t done so yet, don’t forget to check out the free online training program on Structural Stability of Engineered Lumber in Fire Conditions at the UL University developed and provided by Underwriter’s Laboratories (UL),  HERE   

Here’s an additional series of other important Reference Links that provide some insights on operational safety, incident conditions and factors ;   

  • NIOSH Publication No. 2009-114: Preventing Deaths and Injuries of Fire Fighters Working Above Fire-Damaged Floors HERE
  • NIOSH Publication No. 2005-132: Preventing Injuries and Deaths of Fire Fighters Due to Truss System Failures HERE
  • NFPA Report on Light Weight Construction, HERE
  • Informative USFA Coffee Break series postings related to Building Types & Fire Resistance:  HERE. HEREHERE, HERE, and HERE
  • Remember, Building Knowledge = Firefighter Safety (Bk-F2S)

Buildingsonfire.com and the Command Institute

  

Coming Spring 2011

We’re finishing up with the content development and working on the supportive case studies and interactive group activities for an exciting new one day seminar program on that will address the leading issues, studies and reports specific to engineered floor and roof systems, incorporating the lastest UL and NIST test data and insights with cutting edge methodolgies and practices for firefighting operations.  

  • Engineered Structural Systems & Fireground Operations will be available for training bookings commencing in May 2011. Contact us for a new brochure and program details.

In addition, look for a new updated 2011 Training Seminar brochure to download with a series of revised training seminars incorporating the newest operational insights  

  • Building Construction for the Command & Company Officer
  • Building Construction and Tactical Operations
  • Tactical Operations and the New Rules of Combat Fire Engagement
  • Dynamic Risk Assessment of Occupancies for Operational Safety
  • Reading the Building: Predictive Profiling Predictive Occupancy Profiling

Prevention of Disproportionate Structural Collapse

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Many U.S. buildings are vulnerable to extreme loads that may cause partial or total collapse. Modern structures have a limited reserve capacity to accommodate abnormal loads. There is no accepted science-base or design practice to maintain overall structural robustness within a multi-hazard context that considers both design loads and abnormal loads. The National Institute of Standards and Technology (NIST) is an agency of the U.S. Commerce Department, has initiated a new project will address the development of procedures and computational methodologies for assessment of overall structural robustness and will provide the measurement science needs for the development of performance-based provisions in U.S. codes and standards for disproportionate collapse resistance that will ensure improved robustness of building structures.  

The term “disproportionate collapse” is defined as the spread of an initial local failure from element to element resulting in the collapse of an entire structure or a disproportionately large part of it.

Since the terrorist attacks on the WTC towers and the Pentagon, owners of major U.S. buildings including the federal government (the largest single owner of buildings in the U.S.)  have emphasized disproportionate collapse resistance as one of the design requirements (see, e.g., Senate Committee Report 107-57). Currently, GSA, DoD, and DoS require that their buildings be designed and evaluated for disproportionate collapse potential. The NIST WTC Towers Investigation (NIST NCSTAR 1, Recommendation 1) calls for the development of consensus-based codes and standards for disproportionate collapse mitigation, and was reiterated in the investigation of the fire-induced disproportionate collapse of WTC 7 (NIST NCSTAR 1A).

There are no metrics to compare the overall system-level performance of structures, making it impossible to compare and quantify the safety performance of different types of structural systems. There is no accepted science-base or design practice to maintain overall structural robustness within a multi-hazard context that considers both design loads and abnormal loads. Critical measurement science capabilities that are lacking include;

 (1) system-level structural models capable of estimating the reserve capacity of building structures and assessing disproportionate collapse resistance,

(2) measures of structural robustness, and

(3) proven and cost-effective methods to mitigate disproportionate collapse.

The behavior of structural systems near their ultimate limit states is not well understood, and simulating this behavior depends on the availability of accurate structural models. Development of accurate models to predict reserve capacity of structural systems and allow the quantification of robustness, in turn, depends on the availability of validated models of members and connections. At the present time, experimental data on the behavior of connections undergoing disproportionate collapse are lacking. In addition, detailed modeling of a complete structural system to failure is often beyond the capability of existing tools. Reduced models of connections that capture the predominant behaviors and failure modes are needed for cost effective assessment of structural robustness and disproportionate collapse potential.  

While the measurement science needs identified above have not been solved, organizations in the U.S. such as NIST, ERDC, DTRA, and GSA as well as few universities in Belgium, England, and Japan have conducted limited testing of full and scaled models of steel subassemblies. No concrete subassemblies have been tested anywhere. Over the past few years, organizations such as NIST and a few private sector companies under contract to federal agencies have made some progress in the modeling of subassemblies; both at the detailed and reduced models levels. However, measurement science needs such as metrics for structural system robustness, system-level computational tools, and agreed-upon methods for disproportionate collapse mitigation have not been developed.  

This project will provide the measurement science needs for the development of performance-based provisions in U.S. codes and standards for disproportionate collapse resistance that will ensure resilience of building structures and as a result improve life safety and thereby improving the quality of life. Furthermore, the project is part of the “Measurement Science for Structural Performance under Multi-Hazards” program within EL’s strategic goal on “Measurement Science for Disaster Resilient Structures and Communities”. EL is well positioned to address the needs outlined in this project because of its long history in investigating structural failures and the capabilities built over the years in analyzing the failures of complex multi-story structures using state of the art computational tools.  

What is the new technical idea? A key focus of the project is to develop system-level performance metrics to quantify the robustness of building structures. Robustness is a key structural property that is related to disproportionate collapse resistance. Both structural redundancy and integrity are key factors that influence the robustness of the structure. These factors must be quantified to express the robustness in a meaningful and measurable manner. The assessment of the degree of structural redundancy for redistribution of loads and structural integrity for system continuity requires simulation of structural behavior under various local failure scenarios. Realistic and efficient simulations require the development and use of advanced and experimentally validated modeling methodologies to examine the structural system performance. Both traditional and new design concepts will be evaluated to determine the relative merits of various structural systems in resisting disproportionate collapse. The project will examine collapse limit states of structural systems to quantify the reserve capacity of various structural systems, through a combination of push-down and push-over analyses. The project will also develop design and retrofit methodologies that take explicit advantage of the synergies associated with mitigating disproportionate collapse under multiple hazards to enhance overall efficiency and cost-effectiveness.  The required work depends heavily on the use of advanced and detailed structural models to evaluate the nonlinear behavior of structural systems in post ultimate capacity limit states. With today’s high-performance computational tools, it is feasible to predict structural response due to abnormal dynamic loads. Complementary to the analytical evaluation of structures, the project will review and make use of the knowledge gained from controlled demolition technology. Through decades of experience, the demolition community has developed detailed knowledge about the collapse behavior of structural systems.  

The recommendations from a national workshop formed the basis for a coordinated national plan for problem-focused research on mitigation of disproportionate collapse of buildings. The project proposes to develop metrics to quantify the robustness of various structural systems to assess their disproportionate collapse potential. These metrics will be based on experimentally validated computational models of structural systems incorporating the predominant behaviors and failure modes of components and connections. Such models can also be used by design professionals in design for disproportionate collapse resistance. A key component in the development and evaluation of robustness metrics will be a series of push-down and push-over analyses to assess the reserve capacity of a variety of structures with different systems and materials. The project will develop performance objectives, acceptance criteria, and evaluation methods for both new and existing structures, which will be used to develop guidance documents and pre-standards for design and rehabilitation of structures to mitigate disproportionate collapse.  

The NIST  project will produce the following outcomes:

1. Best Practices Guide for design of new buildings and rehabilitation of existing buildings (Complete).

2. Computational methodologies to evaluate the disproportionate collapse potential of building structures for practicing engineers based on the following work:

Experimental:

(a) testing of full-scale subsystems to validate detailed computer models.

(b) testing of 3-D multi-story frames to validate reduced 3-D computer models.

Computational:

(a) development of reduced 3-D models of various structural systems.

(b) comparative assessment of reserve capacities of various structural systems.

(c) evaluation of structural systems capable of resisting disproportionate collapse.

3. Guidelines for assessing disproportionate collapse vulnerability, including both rapid and comprehensive evaluation guides.

4. Comprehensive guidelines for design of new buildings to resist disproportionate collapse.

5. Comprehensive guidelines for retrofit of existing buildings to resist disproportionate collapse.

6. Pre-standards for design of new buildings and retrofit of existing buildings to resist disproportionate collapse. 

FY 2010 the projects overview: 

  1. Development of 3-D structural models of 10-story reinforced concrete shear wall and precast concrete buildings.
  2. Evaluation of reserve capacity and development of structural robustness metrics for various structural systems.
  3. Evaluation and comparison of disproportionate collapse vulnerability of various steel and reinforced concrete structural systems.
  4. Design and testing of precast concrete beam-column assemblies.

Major Accomplishments:

Recent Results: 

Impact                 

Best Practices Guide (NISTIR 7396) adopted by ASCE 7-10 Standard as part of the commentary section on General Structural Integrity. 

Outcomes

  • Developed experimentally validated 3D models of steel frame buildings for assessment of reserve capacity and vulnerability to disproportionate collapse (Journal publication being developed).
  • Developed experimentally validated 3D models of reinforced concrete frame buildings for assessment of reserve capacity and vulnerability to disproportionate collapse (Journal publication being developed). 
  • Published “Best Practices for Reducing the Potential for Progressive Collapse in Buildings-NISTIR 7396.”    

The National Institute of Standards and Technology (NIST) http://www.nist.gov/index.html

Building Behaving Badly

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Buildings Behaving Badly; Ok, it’s been a very quiet morning. Nothing much in the way of any work or excitment. The bells come in….Your company gets a dispatch for a report of walls showing signs of cracking and movement in the building. You arrive at curb side with the balance of the one and one assignment to find that you have a thirteen story apartment building lying in its  side on the ground. Now; how are you going to transmit that “on-scene size-up and status report?”…..The following are a series of exceptional photos from of all places China that depict a thirteen story apartment building that clearly behaved badly. The unoccupied apartment building toppled over due a series of design flaws and environmental factors. “Engine 21 to dispatch….can you fill the box and strike a fifth alarm…reporting a thirteen story apartment building laying on the ground……”  “Oh, and by the way; you may want to notify the Fire Chief on this one….”

 001 

There are some of the known facts;

  • An underground garage was being dug on the south side, to a depth of 15 feet (4.6 meters)
  • The excavated dirt was being piled up on the north side, to a height of 33 feet (10 meters)
  • The building experienced uneven lateral pressure from south and north
  • This resulted in a lateral pressure of 3,000 tonnes; which was greater than what the pilings could tolerate.
  • The building was evacuated as conditions were becoming obvious that there was a problem
  • The Building was constructed on grade with no basement foundation a series of pilings

    The Building was constructed on grade with no basement foundation a series of pilings

    Construction was started on the north side of the building for an underground garage to be built. The excavated soil was piled on the south side of the building

    Construction was started on the north side of the building for an underground garage to be built. The excavated soil was piled on the south side of the building

    Environmental conditions-Heavy Rains resulted in significant water saturation into the ground and foundation

    Environmental conditions-Heavy Rains resulted in significant water saturation into the ground and foundation

    The building began to shift due to the tremendous uneven lateral forces being applied from the soil pile, water saturation and soil movement in the foundation. This caused the concrete pilings to snap at the base

    The building began to shift due to the tremendous uneven lateral forces being applied from the soil pile, water saturation and soil movement in the foundation. This caused the concrete pilings to snap at the base

    This caused the building to begin a slow tilt, followed by it toppling over in one unified piece

    This caused the building to begin a slow tilt, followed by it toppling over in one unified piece

    007

    Thus the entire building toppled over in the southerly direction.If the adjacent Apartment buildings were closer in proximity, the likelihood of domino effect would have occurred.

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    009

     0010

     0011

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    The Apartment Building was built to a height of 13 stories, on grade with no basement or foundation. It was "anchored" to grade with "Hollow" concrete pilings with NO reinforcing bars

    The Apartment Building was built to a height of 13 stories, on grade with no basement or foundation. It was "anchored" to grade with "Hollow" concrete pilings with NO reinforcing bars

    Building Types

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    newyork-ogleThe United States Fire Administration (USFA) recently published a series of bulletins under their highly acclaimed Coffee Break Training series of informational bulletins. This series provided insights and awareness of how Buildings are “types” from a codes perspective related to fire resistance. All firefighters and officers need to have a firm understanding of the principles, concepts and methodologies of building construction. Another mission critical concept that I’ve discussed recently is operational risks and tactical deployment must be based upon Occupancy Risk, not Occupancy Type.

    Remember; Building Knowledge = Firefighter Safety.

    Here are the USFA document links;

    Part 1: Understanding Construction “Types, HERE

    Part 2: Where Fire Resistance May Be Required, HERE

    Part 3: Fire-Resistive Assemblies, HERE

    Part 4: How Fire Resistance Ratings are measured, HERE

    Part 5: Understanding Construction: Fire Test “Survival”, HERE

    Part 6: Required Fire Resistance, HERE

    Part 7: Fire Resistance Based on Separation, HERE

    More on Building Types in an upcoming post.

    UL Fire Resistive Assemblies Information, HERE

    Rating Definitions, HERE